This invention relates to a clutch used in a blender assembly for connecting the blender motor to the rotatable cutter assembly inside a blender jar.
It is not uncommon for a user to turn on a blender and leave it unattended, even if just for a few seconds. If a blender jar is not secure or well-seated on its blender base, the blender jar can pop off and cause a mess.
In some high use environments, for instance, commercial settings, if a blender falls off its base, then there could be a spill and a waste of valuable time. Also, a user can misuse a blender assembly by, for instance, putting ajar on its motor housing/base and turning on the motor prematurely, or similarly, pulling the jar off of the base before the motor stops rotating. In addition to the potential mess that this could cause, these abusive practices could be damaging to the appliance. One area that is commonly damaged is the coupling made up of the two clutches where the clutch teeth can become chipped or even shear off.
Some efforts at solving the foregoing problems include clutches made of rubber and having vertical drive faces on the teeth of the clutches. A vertical drive face facilitates alignment of the clutch teeth upon mounting of a blender jar on the base. The trade-off is that the vertical drive face does not necessarily grip ajar onto the base as securely as possible.
Accordingly, it is an object of the present invention to solve the foregoing problems and provide a clutch having teeth wherein the drive face of those clutch teeth has a negative draft.
In one embodiment, a coupling for a blender comprises first and second clutches. The first clutch is connected to a blender motor and is adapted to be rotatably driven by operation of the motor. The second clutch is connected to a rotatable cutter assembly inside a blender jar. The first and second clutches each comprise a plurality of teeth, and each tooth comprises a drive face. Each drive face has a negative draft. In a further variation, the first and second clutches may be comprised of metal, including cast aluminum. Each clutch may comprise four teeth, with each tooth oriented on the clutch about 90xc2x0 from its adjacent teeth. The negative draft of each drive face may be in the range of 1xc2x0 to 10xc2x0. The negative draft may be approximately 5xc2x0. Still further, the negative draft of each drive face can be substantially the same.
In a further embodiment, a blender comprises a rotatable cutter assembly, a jar for receiving a material to be acted upon by said rotatable cutter assembly which is positioned within the jar, and a motor carried in a housing with a drive shaft. A coupling comprises first and second clutches. The first clutch is connected to the motor by the drive shaft and is adapted to be rotatably driven by operation of the motor. The second clutch is connected to a rotatable cutter assembly inside the jar. The first and second clutches each comprise a plurality of teeth, and each tooth comprises a drive face wherein each drive face has a negative draft. Alternatively, the first and second clutches may be comprised of metal, including cast aluminum. Each clutch may comprise four teeth, with each tooth oriented on the clutch about 90xc2x0 from its adjacent teeth. The negative draft of each drive face can be in the range of 1xc2x0 to 10xc2x0. Alternatively, the negative draft of each drive face can be approximately 5xc2x0. Still further, the negative draft of each drive face can be substantially the same.